It depends on a lot of factors, When I worked up in the northern states, We just repacked them and the would last for a vary long time. When I worked in Las Vegas in that kind of heat, we had a lot more bearing related repairs. Nowadays they have the sealed bearings. Can't repack these suckers. They seem to go defective whenever they feel like it. However, if your going through a wheel bearing in say a year or less, then you most likely have another problem.
